DIO5538B 5~100mA,Single Li-ion Battery Charger

Transcription

1 5~100mA,Single Li-ion Battery Charger Rev 1.1 Features Broad Programmable Charging Current: 5~100mA Over-Temperature Protection Under Voltage Lockout Protection Reverse current protection between BAT and GND pins Automatic Recharge Threshold 4.05V(Typ.) Charge Status Output Pin 2.9V Trickle Charge Threshold Soft-Start Limits Inrush Current Over Voltage Lockout Protection <0.35mm thickness super thin DFN package Descriptions The DIO5538B is a complete constant-current / constant voltage linear charger for single cell Lithium-Ion batteries. No external sense resistor is needed, and no blocking diode is required due to the internal MOSFET architecture. Thermal feedback regulates the charge current to limit the die temperature during high power operation or high ambient temperature. The charge voltage is fixed at 4.2V, and the charge current can be programmed externally with a single resistor. The DIO5538B automatically terminates the charge cycle when the charge current drops to 1/10 the programmed value after the final float voltage is reached. When the input supply (wall adapter or USB supply) is removed, the DIO5538B automatically enters a low current state, dropping the battery drain current to less than 0.5µA. The DIO5538B can be put into shutdown mode, reducing supply current to 40µA (Typ.). The DIO5538B is available in a small package with DFN1.8*2-6. Standard product is Pb-Free. Ordering Information Applications Wireless phone MP3/MP4 Player Bluetooth device Order Part Number Top Marking T A Package DIO5538BCN6 538B Green -40 to +85 C DFN1.8*2-6 Tape & Reel, 3000 DIO5538B Rev. 1.1

2 Pin Assignment Pin Descriptions Name PROG DIO5538B DFN1.8*2-6 Figure 1. Top View Description Charge current setting, charge current monitor and shutdown pin. The charging current is given by I BAT= (1/R PROG)*100. The chip will be shutdown when PROG pin floating. GND VCC Ground. Power Supply. BAT Charge Current Output. Provides charge current to the battery an regulates the final float voltage to 4.2V. CHRGb Open-Drain Charge Status Output. When the battery is charging, the CHARGb pin is pulled low. When the charge cycle is completed or VCC is removed, the CHARGb is forced high impedance. TEMP GND(Expose Pad) Battery Temperature Sense Pin. When the battery temperature is too high or too low, the charging current will be terminated. This pin must be connected to GND, and punch to the main GND to facilitate heat dissipation.

3 Absolute Maximum Ratings Stresses beyond those listed under Absolute Maximum Rating may cause permanent damage to the device. These are stress ratings only and functional operation of the device at these or any other condition beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maxim rating conditions for extended periods may affect device reliability. Parameter Rating Unit Supply Voltage -0.3~10 V PROG Voltage -0.3~VCC V BAT Voltage -0.3~10 V CHRGb Voltage -0.3~VCC V BAT Pin Current 100 ma Power Dissipation 0.6 W Junction Temperature 150 C Storage Temperature -65~125 C Lead Temperature (Soldering 10s) 260 C Recommend Operating Conditions The Recommended Operating Conditions table defines the conditions for actual device operation. Recommended Operating conditions are specified to ensure optimal performance to the datasheet specifications. DIOO does not Recommend exceeding them or designing to Absolute Maximum Ratings. Parameter Rating Unit Input Supply Voltage 4.5 to 5.5 V Operating Temperature Range -40 to 85 C

4 Electrical Characteristics VCC=5V, T A = 25 C (unless otherwise noted) Symbol Parameter Conditions Min. Typ. Max. Unit R PROG=10kΩ µa I SOLYCHRG Charge Mode Supply Current R PROG=20kΩ µa R PROG=5kΩ ma I BATCHRG V PROGCHRG Charge Mode Battery Current R PROG=10kΩ ma R PROG=20kΩ ma R PROG=10kΩ V PROG Pin Voltage R PROG=20kΩ V I SPLYSTBY Standby Mode Supply Current Charge Terminated µa I BATSTBY Standby Mode Battery Current Charge Terminated µa I SPLYASD Shutdown Mode Supply Current V CC<V BAT µa I BATASD Shutdown Mode BAT Pin Current V CC<V BAT ±0.05 ±1 µa I SPLYUVLO UVLO Mode Supply Current V CC<V UV µa I BATUVLO UVLO Mode BAT Pin Current V CC<V UV ±0.05 ±1 µa I SPLYOVLO OVLO Mode Supply Current V CC>V OV 40 µa I BATOVLO OVLO Mode BAT Pin Current V CC>V OV ±0.05 ±1 µa I SPLYSHUT Shutdown Mode Supply Current R PROG not Connected µa I BATSHUT Shutdown Mode BAT Pin Current R PROG not Connected ±0.05 ±1 µa I BATMSD Manual Shutdown BAT Pin Current V PROG=1.3V ±0.05 ±1 µa I BATSLEEP Sleep Mode BAT Pin Current V CC=0V ±0.05 ±1 µa I Charge_terminated 10mA/1mA charger terminated R PROG=10kΩ 10 µa V Charge_terminated R PROG=10kΩ 100 mv V FLOAT Float Voltage V I TRIKL Trickle Charge Current R PROG=10kΩ 1 ma V TRIKL Trickle Charge Voltage Threshold R PROG=10kΩ V V TRIKL, HYS Trickle Charge Voltage Hysteresis R PROG=10kΩ 100 mv V UVLO UVLO Threshold From V CC Low to High V

5 Electrical Characteristics (continued) VCC=5V, T A= 25 C (unless otherwise noted) Symbol Parameter Conditions Min. Typ. Max. Unit V UVLO, HYS UVLO Hysteresis 250 mv V OVLO OVLO Threshold From V CC Low to High 6 V V OVP_Hys OVLO Hysteresis 180 mv V MSD V ASD Manual Shutdown Threshold Voltage Vcc-VBAT Lockout Threshold Voltage PROG Pin Rising PROG Pin Falling V CC from low to High V CC from High to Low V VRECHRG Auto Recharge Battery Voltage mv V CHRGb CHRGb Pin Output Low Voltage I CHRGb=5mA V T LIM Junction Temperature In CT Mode 165 C T SS Soft-Start Time R PROG=2kΩ 50 µs V mv mv T RECHRG Recharge Comparator Filter Time 2 ms T TERM Termination Comparator Filter Time 1 ms I PROG PROG Pin Pull-up Current µa V TEMP_EN Battery Temperature Detect Function Threshold Volatge TEMP Pin Rising TEMP Pin Falling V V V TEMP_H TEMP Pin High Threshold Voltage TEMP Pin Rising TEMP Pin Falling %V CC %V CC V TEMP_L TEMP Pin Low Threshold Voltage TEMP Pin Rising TEMP Pin Falling %V CC %V CC Specifications subject to change without notice.

6 Typical Performance Characteristics VCC=5V, T A= 25 C (unless otherwise noted) PROG Pin Voltage vs. Ambient Temperature Float Voltage vs. Ambient Temperature Icharge vs. Ambient Temperature I trickle charge vs. Ambient Temperature Charge Current vs. Battery Voltage

7 VCC Start-up VCC Shut-down (VCC=5V, R PROG=10kΩ,C BAT=10µF,BAT connect to battery) (VCC=5V, R PROG=10kΩ,C BAT=10µF,BAT connect to battery) Charging Curve (VCC=5V, R PROG=10kΩ,C BAT=10µF) V BAT (VCC=5V, R PROG=10kΩ,C BAT=10µF)

8 Block Diagram TEMP CHRGb 165 C TDIE 80%Vcc 45%Vcc TA C4 C5 SHDNb To BAT C3 2.9V CA C1 C2 1X VCC MA R3 1V R4 0.3V R5 1uA Vcc 5uA VA REF 1.2V 1000X R1 R2 BAT PROG GND Figure 2. Function Block Diagram Operation information The DIO5538B is a single cell Lithium-Ion battery charger using a constant-current / constant-voltage algorithm. It can deliver up to 100mA of charge current with a final float voltage accuracy of ±1%. The DIO5538B includes an internal P-channel power MOSFET and thermal regulation circuitry. No blocking diode or external current sense resistor is required; thus, the basic charger circuit requires only two external components. Furthermore, the DIO5538B is capable of operating from a USB power source. Normal charge cycle A charge cycle begins when the voltage at the VCC pin rises above the UVLO threshold level and a 1% program resistor is connected from the PROG pin to ground or when a battery is connected to the charger output. If the BAT pin is less than 2.9V, the charger enters trickle charge mode. In this mode, the DIO5538B supplies approximately 1/10 the programmed charge current to bring the battery voltage up to a safe level for full current charging. When the BAT pin voltage rises above 2.9V, the charger enters constant-current mode, where the programmed charge current is supplied to the battery. When the BAT pin approaches the final float voltage, the DIO5538B enters constant-voltage mode and the charge current begins to decrease. The charge cycle ends when the PROG voltage is less than 100mV.

9 Programming charge current The charge current is programmed using a single resistor from the PROG pin to ground. The battery charge current of constant current mode is 100 times the current out of the PROG pin. The program resistor and the charge current of constant current are calculated using the following equations: Charge termination I CHRG 1V = R PROG A charge cycle is terminated when the charge current falls to 1/10 of the programmed value after the final float voltage is reached. This condition is detected by using an internal, filtered comparator to monitor the PROG pin. When the PROG pin voltage falls below 100mV for longer than T TERM (typically 1ms), charging is terminated. The charge current is latched off and the DIO5538B enters standby mode, where the input supply current drops to 136µA. (Note: CC/10 termination is disabled in trickle charging mode and thermal limiting modes). When charging, transient loads on the BAT pin can cause the PROG pin to fall below 100mV for short periods of time before the DC charge current has dropped to 1/10 of the programmed value. The 1ms filter time (T TERM ) on the termination comparator ensures that transient loads of this nature do not result in premature charge cycle termination. Once the average charge current drops below 1/10 of the programmed value, the DIO5538B terminates the charge cycle and ceases to provide any current through the BAT pin, the chip will be put into standby mode. In this state, all loads on the BAT pin must be supplied by the battery. 100 Figure 3. State Diagram of a Typical Charge Cycle

10 The DIO5538B constantly monitors the BAT pin voltage in standby mode. If this voltage drops below the 4.05V recharge threshold (V RECHRG ), another charge cycle begins and current is once again supplied to the battery. The state diagram of a typical charge cycle is as Figure 3. Charge status indicator DIO5538B has an open-drain status indicator output CHRGb. CHRGb is pull-down when the DIO5538B in a charge cycle. In other status CHRGb is in high impedance. CHRGb is in high impedance when the battery out of the normal temperature. Represent in failure state, when TEMP pin in typical connecting, and the charger with no battery: red LED don t light. The battery temperature sense function is disabled by connecting TEMP pin to GND. If battery is not connected to charger and the BAT pin connects a 10µF capacitor, the frequency of CHRGb flickers is about 1-4s. Charger state Red GHRGb Charging light Battery in full state dark UVLO, Battery temperature dark is outside TEMP range, battery is note connected (Use TEMP) BAT pin is connected to 10µF and no battery mode (TEMP=GND) Red LED flicker and the frequency is 1~4s Thermal Limiting An internal thermal feedback loop reduces the programmed charge current if the die temperature attempts to rise above a preset value of approximately 165 C. This feature protects the DIO5538B from excessive temperature and allows the user to push the limits of the power handling capability of a given circuit board without risk of damaging the DIO5538B. The charge current can be set according to typical (not worst-case) ambient temperature with the assurance that the charger will automatically reduce the current in worst-case conditions. Battery Temperature Sensing To prevent the damage caused by the very high or very low temperature done to the battery pack, the DIO5538B continuously senses the battery pack temperature by measuring the voltage at TEMP pin determined by the voltage divider circuit and the battery s internal NTC thermistor. The DIO5538B compares the voltage at TEMP pin (V TEMP ) against its internal V LOW and V HIGH thresholds to determine if charging is allowed. In DIO5538B, V LOW is fixed at 45% V CC, while V HIGH is fixed at 80% V CC. If V TEMP <V LOW or V TEMP >V HIGH, it indicates that the battery temperature is too high or too low and the charge cycle is suspended. When the V TEMP is between V LOW and V HIGH, charging cycle resumes. The battery temperature sensing function can be disabled by connecting the TEMP pin to GND.

11 Selecting R1 and R2 The values of R1 and R2 in the application circuit (Figure1) can be determined according to the assumed temperature monitor range and thermistor s values. The Follows is an example: Assume temperature monitor range is T L ~T H, (T L <T H ); the thermistor in battery has negative temperature coefficient (NTC), R TL is thermistor s resistance at T L,R TH is the resistance at T H,so R TL >R TH,then At temperature TL, the volatge at TEMP pin is: At temperature TH, the volatge at TEMP pin is: Because VTEMPL = VHIGH = K2 VCC( K2 = 0.8) V TEMPH = VLOW = K K 1 VCC( 1 = 0.45) R // R R + R // R 2 TL V TEMPL = 1 2 TL R // R R + R // R 2 TH V TEMPH = 1 2 TH Then we can have: RTL RTH( K2 K1) R1 = ( RTL RTH) K1 K2 V V CC CC R2 = R TL ( K 1 RTL RTH( K K1 K2) R 2 TH K1) ( K2 K 1 K2) Likewise, for positive temperature coefficient thermistor in battery, we have R TH >R TL and we can calculate: R2 = R TH R R1 = ( R ( K 1 TH TH RTL( K2 K1) RTL) K1 K2 RTH RTL( K2 K1 K2) R K1) ( K2 K TL 1 K2) We can conclude that temperature monitor range is independent of power supply voltage V CC and it only depends on R1, R2, R TL and R TH : The values of R TH and R TL can be found in ralated battery handbook or deduced from testing data. In actual application, if only one terminal temperature is concerned (normally protecting overheating), there is no ennd to use R2 but R1. It becomes very simple to calculate R1 in this case. Undervoltage Lockout (UVLO) An internal undervoltage lockout circuit monitors the input voltage and keeps the charger in shutdown mode until V CC rises above the undervoltage lockout threshold. The UVLO circuit has a built-in hysteresis of 250mV. Furthermore, to protect against reverse current in the power MOSFET, the UVLO circuit keeps the charger in shutdown mode if V CC falls to within 50mV of the battery voltage. If the UVLO comparator is tripped, the charger will not come out of shutdown mode until V CC rises 120mV above the battery voltage. Overvoltage Lockout (OVLO) An internal overvoltage lockout circuit monitors the input voltage and keeps the charger in shutdown mode until V CC fall down the overvoltage lockout threshold. The OVLO circuit has a built-in hysteresis of 180mV. Furthermore, to protect against reverse current in the power MOSFET, the OVLO circuit keeps the charger in

12 shutdown mode if V CC falls to within 50mV of the battery voltage. If the OVLO comparator is tripped, the charger will not come out of shutdown mode until V CC rises 120mV above the battery voltage. Manual Shutdown At any point in the charge cycle, the DIO5538B can be put into shutdown mode by removing R PROG thus floating the PROG pin. This reduces the battery drain current to less than 1µA and the supply current to less than 50µA. A new charge cycle can be initiated by reconnecting the program resistor. In manual shutdown, The CHRGb pin is in a high impedance state if the DIO5538B is in manual shutdown mode or in the undervoltage lockout mode: either VCC is within 120mV of the BAT pin voltage or insufficient voltage is applied to the VCC pin. Figure 4. Manual Shutdown Mode Application Circuit Automatic recharge Once the charge cycle is terminated, the DIO5538B continuously monitors the voltage on the BAT pin using a comparator with a 2ms filter time (T RECHRG ). A charge cycle restarts when the battery voltage falls below 4.05V (Typ.) (which corresponds to approximately 80% to 90% battery capacity). This ensures that the battery is kept at or near a fully charged condition and eliminates the need for periodic charge cycle initiations. CHRGb output enters a pull-down state during recharge cycles.

13 Application Information Typical Application Figure 5. Typical applications W/T LED indicate Figure 6. Typical applications W/T microprocessor detect Stability considerations The constant-voltage mode feedback loop is stable without an output capacitor provided a battery is connected to the charger output. With no battery present, an output capacitor is recommended to reduce ripple voltage. When using high value, low ESR ceramic capacitors, it is recommended to add a 1Ω resistor in series with the

14 capacitor. No series resistor is needed if tantalum capacitors are used. In constant-current mode, the PROG pin is in the feedback loop, not the battery. The constant-current mode stability is affected by the impedance at the PROG pin. With no additional capacitance on the PROG pin, the charger is stable with program resistor values as high as 50KΩ. However, additional capacitance on this node reduces the maximum allowed program resistor thus it should be avoided. Thermal Limit An internal thermal feedback loop reduces the programmed charge current if the die temperature attempts to rise above a preset value of approximately 165 C. This feature protects the DIO5538B from excessive temperature and allows the user to push the limits of the power handling capability of a given circuit board without risk of damaging the DIO5538B. The charge current can be set according to typical (not worst-case) ambient temperature with the assurance that the charger will automatically reduce the current in worst-case conditions. Power dissipation The conditions that cause the DIO5538B to reduce charge current through thermal feed-back can be approximated by considering the power dissipated in the IC. Nearly all of this power dissipation is generated by the internal MOSFET. This is calculated to be approximately: P D = ( VCC VBAT) It is important to remember that DIO5538B applications do not be designed for worst-case thermal conditions since the IC will automatically reduce power dissipation when the junction temperature reaches approximately 165 C (Constant temperature mode). I BAT VCC bypass capacitor Many types of capacitors can be used for input bypass, however, caution must be exercised when using multilayer ceramic capacitors. Because of the self-resonant and high Q characteristics of some types of ceramic capacitors, a 10µF ceramic capacitor is recommended for this bypass capacitor. Due to a high voltage transient will be generated under some start-up conditions, such as connecting the charger input to a live power source. Charge current soft-start The DIO5538B includes a soft-start circuit to minimize the inrush current at the start of a charge cycle. When a charge cycle is initiated, the charge current ramps from zero to the full-scale current over a period of approximately 100µs. This has the effect of minimizing the transient current load on the power supply during start-up.

15 Physical Dimensions: DFN-6 2*1.8 COMMON DIMENSIONS (UNITS OF MEASURE=MILLIMETER) Symbol MIN NOM MAX A A A3 0.10REF b b D D E E e e K L

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